This building, designed by the noted modernist architect, Eero Saarinen, consists of a spherical segment dome-shaped concrete roof enclosing a triangular area approximately 160 feet on a side. The primary building function is the enclosure of an 1238 seat auditorium and associated lobbies, restrooms, and projection facilities. The dome is entirely supported on three points at the vertices of the triangle, or was by the original design. As every article written on the dome seems to mention, the total weight of the roof is approximately 1500 tons, and the thickness of the roof shell is 3 1?2 inches, thickened to 18 inches at the perimeter. *** The Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, commissioned renowned architect Eero Saarinen to design a 1,200-seat auditorium and 200-seat theater in 1950. Anderson, Beckwith & Haible of Boston were the associate architects. The consulting engineer was Ammann & Whitney of New York, which had previous thin-shell experience. The building was named in honor of chain-store magnate Sebastian S. Kresge, whose foundation donated $1.5 million towards the cost of the auditorium and an adjacent cylindrical chapel, also designed by Saarinen. Kresge, a strong advocate of higher education, had previously funded the construction of a building at the Harvard Business School. *** The building’s roof structure is a spherical dome. However, because of the interruptions to the doubly-curved spherical shape due to the triangular plan of the building, severe edge disturbances to the membrane stresses in the shell result. This requires the addition of a stiffening beam around the perimeter of the building. The thickening of the shell to18 inches at the perimeter is intended to provide the necessary stiffening to the edge of the shell. A review of the discussion of edge stiffening of shells in Module I can be accessed here. A second ‘shell’ was intended to be provided by the addition of a 2 1?2 inch non-structural layer of gunite (spray-applied concrete), which was initially intended as the substrate for the roofing. Changes during construction permitted the substitution of a lightweight ‘nailable’ concrete material. Source: http://www.arche.psu.edu/thinshells/module%20III/case_study_3.htm